/* Matrix c
*/
#include "3d_all.h"

/*
 * Compute inverse of 4x4 transformation matrix.
 * Code contributed by Jacques Leroy jle@star.be
 * Return GL_TRUE for success, GL_FALSE for failure (singular matrix)
 */
GLfloat *glu_invert_matrix(GLfloat * m, GLfloat * out)
{
/* NB. OpenGL Matrices are COLUMN major. */
#define SWAP_ROWS(a, b) { GLfloat *_tmp = a; (a)=(b); (b)=_tmp; }
#define MAT(m,r,c) (m)[(c)*4+(r)]

  GLfloat wtmp[4][8];
  GLfloat m0, m1, m2, m3, s;
  GLfloat *r0, *r1, *r2, *r3;

  r0 = wtmp[0], r1 = wtmp[1], r2 = wtmp[2], r3 = wtmp[3];

  r0[0] = MAT(m, 0, 0), r0[1] = MAT(m, 0, 1),
    r0[2] = MAT(m, 0, 2), r0[3] = MAT(m, 0, 3),
    r0[4] = 1.0, r0[5] = r0[6] = r0[7] = 0.0,
    r1[0] = MAT(m, 1, 0), r1[1] = MAT(m, 1, 1),
    r1[2] = MAT(m, 1, 2), r1[3] = MAT(m, 1, 3),
    r1[5] = 1.0, r1[4] = r1[6] = r1[7] = 0.0,
    r2[0] = MAT(m, 2, 0), r2[1] = MAT(m, 2, 1),
    r2[2] = MAT(m, 2, 2), r2[3] = MAT(m, 2, 3),
    r2[6] = 1.0, r2[4] = r2[5] = r2[7] = 0.0,
    r3[0] = MAT(m, 3, 0), r3[1] = MAT(m, 3, 1),
    r3[2] = MAT(m, 3, 2), r3[3] = MAT(m, 3, 3),
    r3[7] = 1.0, r3[4] = r3[5] = r3[6] = 0.0;

  /* choose pivot - or die */
  if (fabs(r3[0]) > fabs(r2[0]))
    SWAP_ROWS(r3, r2);
  if (fabs(r2[0]) > fabs(r1[0]))
    SWAP_ROWS(r2, r1);
  if (fabs(r1[0]) > fabs(r0[0]))
    SWAP_ROWS(r1, r0);
  if (0.0 == r0[0])
    return (NULL);

  /* eliminate first variable     */
  m1 = r1[0] / r0[0];
  m2 = r2[0] / r0[0];
  m3 = r3[0] / r0[0];
  s = r0[1];
  r1[1] -= m1 * s;
  r2[1] -= m2 * s;
  r3[1] -= m3 * s;
  s = r0[2];
  r1[2] -= m1 * s;
  r2[2] -= m2 * s;
  r3[2] -= m3 * s;
  s = r0[3];
  r1[3] -= m1 * s;
  r2[3] -= m2 * s;
  r3[3] -= m3 * s;
  s = r0[4];
  if (s != 0.0) {
    r1[4] -= m1 * s;
    r2[4] -= m2 * s;
    r3[4] -= m3 * s;
  }
  s = r0[5];
  if (s != 0.0) {
    r1[5] -= m1 * s;
    r2[5] -= m2 * s;
    r3[5] -= m3 * s;
  }
  s = r0[6];
  if (s != 0.0) {
    r1[6] -= m1 * s;
    r2[6] -= m2 * s;
    r3[6] -= m3 * s;
  }
  s = r0[7];
  if (s != 0.0) {
    r1[7] -= m1 * s;
    r2[7] -= m2 * s;
    r3[7] -= m3 * s;
  }

  /* choose pivot - or die */
  if (fabs(r3[1]) > fabs(r2[1]))
    SWAP_ROWS(r3, r2);
  if (fabs(r2[1]) > fabs(r1[1]))
    SWAP_ROWS(r2, r1);
  if (0.0 == r1[1])
    return (NULL);

  /* eliminate second variable */
  m2 = r2[1] / r1[1];
  m3 = r3[1] / r1[1];
  r2[2] -= m2 * r1[2];
  r3[2] -= m3 * r1[2];
  r2[3] -= m2 * r1[3];
  r3[3] -= m3 * r1[3];
  s = r1[4];
  if (0.0 != s) {
    r2[4] -= m2 * s;
    r3[4] -= m3 * s;
  }
  s = r1[5];
  if (0.0 != s) {
    r2[5] -= m2 * s;
    r3[5] -= m3 * s;
  }
  s = r1[6];
  if (0.0 != s) {
    r2[6] -= m2 * s;
    r3[6] -= m3 * s;
  }
  s = r1[7];
  if (0.0 != s) {
    r2[7] -= m2 * s;
    r3[7] -= m3 * s;
  }

  /* choose pivot - or die */
  if (fabs(r3[2]) > fabs(r2[2]))
    SWAP_ROWS(r3, r2);
  if (0.0 == r2[2])
    return (NULL);

  /* eliminate third variable */
  m3 = r3[2] / r2[2];
  r3[3] -= m3 * r2[3], r3[4] -= m3 * r2[4],
    r3[5] -= m3 * r2[5], r3[6] -= m3 * r2[6], r3[7] -= m3 * r2[7];

  /* last check */
  if (0.0 == r3[3])
    return (NULL);

  s = 1.0f / r3[3];             /* now back substitute row 3 */
  r3[4] *= s;
  r3[5] *= s;
  r3[6] *= s;
  r3[7] *= s;

  m2 = r2[3];                   /* now back substitute row 2 */
  s = 1.0f / r2[2];
  r2[4] = s * (r2[4] - r3[4] * m2), r2[5] = s * (r2[5] - r3[5] * m2),
    r2[6] = s * (r2[6] - r3[6] * m2), r2[7] = s * (r2[7] - r3[7] * m2);
  m1 = r1[3];
  r1[4] -= r3[4] * m1, r1[5] -= r3[5] * m1,
    r1[6] -= r3[6] * m1, r1[7] -= r3[7] * m1;
  m0 = r0[3];
  r0[4] -= r3[4] * m0, r0[5] -= r3[5] * m0,
    r0[6] -= r3[6] * m0, r0[7] -= r3[7] * m0;

  m1 = r1[2];                   /* now back substitute row 1 */
  s = 1.0f / r1[1];
  r1[4] = s * (r1[4] - r2[4] * m1), r1[5] = s * (r1[5] - r2[5] * m1),
    r1[6] = s * (r1[6] - r2[6] * m1), r1[7] = s * (r1[7] - r2[7] * m1);
  m0 = r0[2];
  r0[4] -= r2[4] * m0, r0[5] -= r2[5] * m0,
    r0[6] -= r2[6] * m0, r0[7] -= r2[7] * m0;

  m0 = r0[1];                   /* now back substitute row 0 */
  s = 1.0f / r0[0];
  r0[4] = s * (r0[4] - r1[4] * m0), r0[5] = s * (r0[5] - r1[5] * m0),
    r0[6] = s * (r0[6] - r1[6] * m0), r0[7] = s * (r0[7] - r1[7] * m0);

  MAT(out, 0, 0) = r0[4];
  MAT(out, 0, 1) = r0[5], MAT(out, 0, 2) = r0[6];
  MAT(out, 0, 3) = r0[7], MAT(out, 1, 0) = r1[4];
  MAT(out, 1, 1) = r1[5], MAT(out, 1, 2) = r1[6];
  MAT(out, 1, 3) = r1[7], MAT(out, 2, 0) = r2[4];
  MAT(out, 2, 1) = r2[5], MAT(out, 2, 2) = r2[6];
  MAT(out, 2, 3) = r2[7], MAT(out, 3, 0) = r3[4];
  MAT(out, 3, 1) = r3[5], MAT(out, 3, 2) = r3[6];
  MAT(out, 3, 3) = r3[7];

  return (out);

#undef MAT
#undef SWAP_ROWS
}

GLMATRIX *matrix_all(GLMATRIX * m, BOD * p_pos, QUAT * p_rot, BOD * p_scs)
{
  init_matrix(m);
  if (p_pos) {
    m->_41 = p_pos->x;
    m->_42 = p_pos->y;
    m->_43 = p_pos->z;
  }
  if (p_rot) {
    quat_to_matrix(m, p_rot);
  }
  if (p_scs) {
    scale_matrix(m, p_scs->x, p_scs->y, p_scs->z);
  }
  return (m);
}
